Side Effects of Periactin (cyproheptadine)

Periactin (cyproheptadine) is an oral antihistamine used to treat allergic reactions and the skin manifestations of allergic reactions.

Histamine is released by cells of the body during several types of allergic reactions and, to a lesser extent, during some viral infections, such as the common cold. When the histamine binds to receptors on other cells, it stimulates changes within the cells that lead to the release of chemicals that cause sneezing, itching, and increased production of mucus.

Antihistamines compete with histamine for cell receptors and bind to the receptors without stimulating the cells. In addition, they prevent histamine from binding and stimulating the cells. Cyproheptadine also blocks the action of acetylcholine (anticholinergic effect) and serotonin, two neurotransmitters that nerves and muscles use to communicate with one another, and it causes drowsiness.

Off-label uses (non-FDA approved) of cyproheptadine include for spasticity associated with spinal cord injury and to prevent migraine headaches.

Common side effects of cyproheptadine include

• drowsiness,
• sedation,
• dizziness,
• restlessness,
• insomnia,
• tremors,
• euphoria,
• nervousness,
• irritability,
• numbness and tingling,
• weakness,
• palpitations,
• fast heartbeats,
• high or low blood pressure,
• loss of appetite,
• nausea,
• vomiting,
• diarrhea,
• constipation,
• cholestasis,
• hepatitis,
• eczema,
• itching,
• blurred vision,
• double vision,
• ringing in the ears,
• urinary retention,
• wheezing, and
• stuffy nose. 

Serious side effects of cyproheptadine include

• seizures,
• psychosis, and
• delirium.

Drug interactions of cyproheptadine include

• alcohol,
• benzodiazepines,
• narcotics,
• tricyclic antidepressants, and
• high blood pressure (hypertension) medications that can cause sedation because cyproheptadine adds to the sedating effects.

Cyproheptadine also can intensify the drying effects on moist tissues (such as the eye or mouth) of other medications with anticholinergic properties such as dicyclomine, bethanechol, and probanthine.

Studies in women who are pregnant have not shown that cyproheptadine harms the fetus during the first, second and third trimesters of pregnancy. However, these studies do not exclude the possibility of harm. Cyproheptadine should be used during pregnancy only if it is clearly needed.

It is unknown if cyproheptadine is excreted in breast milk. Consult your doctor before breastfeeding. 

Side effects of include:

• Drowsiness
• Sedation
• Dizziness
• Restlessness
• insomnia
• Tremors
• Euphoria
• Nervousness
• Irritability
• Delirium
• Seizures
• Psychosis
• Paresthesia
• Weakness
• Palpitation
• Fast heart beat
• Palpitation
• High or low blood pressure
• Anorexia
• Nausea
• Vomiting
• Diarrhea
• Constipation
• Cholestasis
• Hepatitis
• Eczema
• Itching
• Blurred vision
• Double Vision
• Ringing in the ears
• Urinary retention
• Wheezing
• Nasal stuffiness

Other side effects that have been reported include:

• Vertigo
• Sweating
• Chills
• Early menses
• Headache
• impotence
• Dryness of mouth, nose, and throat
• Facial dyskinesia
• Tightness of chest

Antihistamines may reduce mental alertness, however, they may occasionally produce excitation in children.

Patients should be warned about driving a car or operating machinery and participating in other activities that require mental alertness and motor coordination.

Antihistamines may add to the sedative effects of alcohol, hypnotics, sedatives, tranquilizers, and anti-anxiety drugs.

Antihistamines are more likely to cause

• dizziness,
• sedation, and
• hypotension (low blood pressure) in elderly patients.

Adverse reactions which have been reported with the use of antihistamines are as follows:

Central Nervous System

Sedation and sleepiness (often transient), dizziness, disturbed coordination, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, paresthesias, neuritis, convulsions, euphoria, hallucinations, hysteria, faintness.

Integumentary

Allergic manifestation of rash and edema, excessive perspiration, urticaria, photosensitivity.

Special Senses

Acute labyrinthitis, blurred vision, diplopia, vertigo, tinnitus.

Cardiovascular

Hypotension, palpitation, tachycardia, extrasystoles, anaphylactic shock.

Hematologic

Hemolytic anemia, leukopenia, agranulocytosis, thrombocytopenia.

Digestive System

Cholestasis, hepatic failure, hepatitis, hepatic function abnormality, dryness of mouth, epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation, jaundice.

Genitourinary

Urinary frequency, difficult urination, urinary retention, early menses.

Respiratory

Dryness of nose and throat, thickening of bronchial secretions, tightness of chest and wheezing, nasal stuffiness.

Miscellaneous

Fatigue, chills, headache, increased appetite/weight gain.

MAO inhibitors prolong and intensify the anticholinergic effects of antihistamines. Antihistamines may have additive effects with alcohol and other CNS depressants, e.g. hypnotics, sedatives, tranquilizers, antianxiety agents.